In a case where cans of rectangular shape or cans of different size and shape are manufactured by seaming a lid to an end portion of a can body by using a curl roller and a tightening roller, a profiling cam has been conventionally prepared that matches the cross-sectional shape of the can body and the can seaming operation has been performed by moving the curl roller and tightening roller with respect to the transverse section of the can. In this case, each time the cross-sectional shape of the can body changes, a new profiling cam has to be used, and the profiling cam replacement is a time-consuming and troublesome operation. Therefore, the automatic production line is stopped when the profiling cam is replaced, thereby causing very large loss. Furthermore, the number of replacement parts increases and these parts are difficult to manage. In addition, adjustments by skilled technicians are required for the profiling cam replacement and can seaming operation, and the cost is difficult to reduce.
Accordingly, in recent years, where cans of different size or shape are manufactured by seaming a lid to an end portion of a can body by using a curl roller and a tightening roller, for example, a can production device such as suggested by Japanese Patent Application Laid-open No. 2001-259766 is employed as a device that uses no profiling cam. With this device, when a can of a cross-sectional shape different from a perfect round shape, for example, of an elliptical shape is processed, it is possible to conduct strain-free uniform seaming such that a curl seam processing line adapted to this can has a constant speed. This production device has a structure such that a can is produced by seaming a can body and lids at both sides of the can body in rotary dies provided at a base seat and a suppressing seat that faces the base seat and can move to and from the base seat, wherein the suppressing seat, rotary dies, curl roller, and tightening roller are coupled to respective servo motors, the cross-sectional shape and height of the can body, number of feed steps of the curl roller and tightening roller, the feed amount for each step, and the rotation speed of the rotary dies are written in a numerical control unit, and the servo motors are successively actuated based on the information written in the numerical control unit.
However, Japanese Patent Application Laid-open No. 2001-259766 mainly relates to a production device that can process cans of a cross-sectional shapes different from a perfectly round shape, such as an elliptical shape, that is used as an outer shell of an automotive muffler, and neither describes nor suggests a can seamer in accordance with the present invention that can process cans of rectangular shape or cans of different size or shape, without using a profiling cam.    Patent Document 1: Japanese Patent Application Laid-open No. 2001-259766